Some networking applications require switching between high numbers of ports. For example, a typical data center includes a large number of servers, and switches configured to communicatively couple the servers to outside network connections, such as backbone network links. As another example, a high-volume website server system (server farm) can include a large number of web servers, and switches to communicatively couple the web servers to backbone network links. More generally, enterprise networks involve large numbers of computers communicatively coupled together via large numbers of network links, which often require switching systems that switch between large numbers of ports.
In such applications, switching systems capable of switching between a large number of ports are utilized. Such switching systems can include a large number of switches, and each switch can be capable of switching between several ports.
Some network switching systems utilize port extenders (PEs) coupled to ports of a controlling bridge (CB) serving as a central switch. Each PE is typically a relatively low complexity device that includes a plurality of ports. When coupled to a port of the CB, the PE serves as a port fan-out for the CB, effectively increasing the number of ports handled by the CB at relatively low cost.
In a typical network switching system employing PEs, a forwarding tag is inserted into a header of a packet ingressing the network switching system, is utilized to forward the packet through the network switching system, and is stripped from the header of the packet when the packet is ultimately egressed from the network switching system. In conventional network switching systems, forwarding tags that conform to a particular format, such as the E-tag format defined by the Institute for Electrical and Electronics Engineers (IEEE) 802.1BR Standard, are utilized.